Completion of the projects outlined will serve to address critical disparity in knowledge of a biologic description of Alzheimer's disease (AD) in African Americans (AA). The GEMSSTAR proposal to which this application is linked seeks to identify a more appropriate cognitive marker for early identification of cognitive impairment for AA. The current proposal further develops this objective by linking this tested cognitive marker to AD Cerebral Spinal Fluid (CSF) biomarkers and imaging. In a cohort of ~120 study participants (>50% with Mild Cognitive Impairment, MCI, who are AA) we propose 1) to assess the levels of AD CSF biomarkers as well as hippocampal thickness per MRI in order to determine the A?1-42 (A), p-tau (T) and extent of neurodegeneration (N) profile, the updated research diagnostic criteria for AD; and 2) Determine if AD CSF biomarkers are associated with impaired executive function. Our overall objective is to contribute A,T,N profile data for AA with MCI as there is a dearth of such data in the National Alzheimer Coordinating Center (NACC) even though the research definition of AD is changing significantly. The Specific Aims to be completed are the following: 1. Compare levels of A?1-42 (A), p-tau (T), and hippocampal volumes (N) in AA and White participants to establish a body of data on CSF correlates of A, T and N with race. Our working hypothesis is that for the same level of cognitive performance, we will observe higher CSF A?1-42 (A), (reflecting lower brain amyloidosis), lower p-tau, and larger hippocampal volumes for AA study participants based on prior observations that vascular factors (hypertension, atherosclerosis, and diabetes) may be greater contributors to cognitive impairment in AA relative to Whites. 2. Determine the differential association between AD CSF biomarkers and various cognitive domains by race. Our working hypothesis is that in AA we will observe a stronger association between AD CSF biomarkers (A and/or T) and executive function (as assessed by the CLOX and Flanker task) than in Whites. The funding of this project will serve to leverage pre-collected CSF biospecimen data for the purpose of applying the new NIA- Alzheimer's Association updated research framework to contribute data for a minimum of 58 AA with MCI to the larger community of AD research cohorts. This proposal comprises data that will be obtained via a cross-sectional study design. CSF from all willing participants not meeting exclusion criteria in the parent study will be analyzed via quantitative analysis for A?1-42, t-Tau, and p-Tau181p. Our primary outcome is the AT(N) biomarker profile and category for at least 58 AA with MCI and 57 without MCI. Additionally completing the analysis of AD CSF biomarkers with executive impairment may serve to link a more sensitive cognitive performance marker in AA to the updated NIA-Alzheimer's Association research framework of AD, yielding a more robust assessment for AA who are often either undiagnosed or diagnosed in more advanced stages of disease.